Vapor discharge tube



1955 H. G. BRUIJNING 2,727,174

VAPOR DISCHARGE TUBE Filed July 2, 1952 //VVE/V7'0/? HUGO GEORGE BRUIJNING AGE/VT United States Patent Ofifice 2,727,174 Patented Dec. 13, 1955 VAPOR DISCHARGE TUBE Hugo Georg Bruijning, Eindhoven, Netherlands, assigner to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application July 2, 1952, Serial No. 2%,907 Claims priority, application Netherlands April 4, 1951 1 Claim. (Cl. 313163) This application is a continuation-in-part of an application, Serial No. 271,830 filed February 15, 1952, by the same inventor.

This invention relates to vapor discharge tubes, in particular, to vapor discharge tubes comprising a mercury pool cathode and a hydrogen gas filling.

Tubes of the foregoing type frequently have a drawback in that they have two difi'erent, comparatively constant, igniting or breakdown voltages which alternately arbitrarily occur. When such a tube is utilized in a pulse generating apparatus, for example, pulses are produced which have unequal amplitudes because of these two arbitrary igniting voltages.

It is an object of this invention to provide a mercury vapor discharge tube having a hydrogen-filling with one constant igniting voltage, particularly for use in an apparatus for producing pulses.

This and further objections of the invention will appear from the description that follows.

According to the invention, a vapor discharge tube comprising a mercury pool cathode and a hydrogenfilling of about 1 to a few atmospheres pressure is provided with a thin layer of a liquid having a low molecular Weight covering the cathode. With such an arrangement, the tube has one constant igniting voltage.

The invention will now be described with reference to the accompanying drawing in which the sole figure shows a mercury vapor discharge tube, in cross-section, in accordance with the invention.

Referring to the drawing, the tube shown comprises an envelope 1, of glass, for example, enclosing a mercury pool cathode 2. An electrically conducting rod 3 of re fractory metal, e. g., molybdenum, which serves as an anode, extends through an opening in the upper wall portion of the envelope 1 and is spatially separated from the cathode 2. The tube is filled with hydrogen to a pressure, at room temperature, of about 1.5 atmosphere.

In order to ensure a constant igniting voltage, a thin layer 4 of a liquid having a low molecular weight, e. g., water covers the surface of the pool cathode 2. Water is preferred although other liquids of low molecular Weight, such as ethyl alcohol, can be used since it is decomposed into oxygen and hydrogen by the are discharge occurring Within the tube which recombines to form Water vapor in the atmosphere of the tube. The water film should be exceedingly thin, i. e., of the order of 0.1 to 0.2 mm. for best results.

While I have thus described my invention with specific examples and embodiments thereof, other modifications will be readily apparent to those skilled in the art without departing from the spirit and the scope of the invention as defined in the appended claim.

What I claim is:

A vapor discharge tube comprising a mercury pool cathode, a hydrogen filling of not more than a few atmospheres, an anode, an envelope enclosing said cathode and said anode, and a layer of water covering said cathode and having a thickness of about 0.1 mm.

Buttolph June 7, 1932 Slepian Ian. 9, 1940 

